The flights were permitted by the United Nations Security Council, which waived an arms embargo on the conflict-ridden country to allow its armed forces to better equip themselves.
At the same time, 175 military trainers -- all but a handful of them private contractors -- arrived from Russia.
In turn, those trainers were followed by Russian companies eager to exploit the Republic's reputed mineral wealth.
Their trip was backed by a foundation -- the Center for Investigation -- run by Russian exile Mikhail Khodorkovsky. A long-time foe of Putin who spent years in prison in Russia, Khodorkovsky wrote on Facebook Wednesday that the journalists were working on a project about "Russian mercenaries."
The deaths of the journalists have focused attention on Russia's growing interest in central Africa, and the relationship between the Kremlin and private Russian companies that combine security work with mining and other activities.
An ill-fated journey
The three men had traveled via Morocco on tourist visas, informing neither the Russian embassy nor CAR authorities of their presence because they wanted to investigate the activities of a Russian military contractor called PMC Wagner, the Center for Investigation said.
Perhaps not surprisingly, the journalists were refused permission to visit a site south of Bangui, where Russian trainers are based at a crumbling palace that belonged to the former ruler of CAR, Jean Bedel Bokassa. Adjacent to the palace is a long runway.
Instead, the three journalists headed north towards a gold mine at Ndassima, operated by a Russian firm and guarded by Russian contractors. But the Center for Investigation says they strayed from their planned route.
According to CAR officials, the journalists had ignored advice not to travel after dark and were ambushed some twenty miles (32 kilometres) north of the town of Sibut. They were shot dead by men wearing turbans and speaking Arabic after refusing to surrender their vehicle and equipment, the officials said. Their driver survived and raised the alarm.
Alain Nzilo, a journalist in CAR who has covered the growing Russian presence, told CNN he was surprised by the location of the ambush. The rebel presence in the area had declined in recent months, there are UN peacekeeping patrols in the area, and the military operates in Sibut.
Nzilo also found it strange that the rebels appeared to have let the driver go free. "Often, the drivers are the first to be killed and not the foreigners," he told CNN.
The Wagner effect
PMC Wagner is a secretive company -- with no known address, phone number or official records -- that recruits hundreds of former Russian soldiers, many of them special forces or "spetsnaz." In the last few years, its contractors have appeared in a growing number of conflict zones.
Wagner was sanctioned by the United States
last year for its involvement with separatists in eastern Ukraine. It has also played a major role in Syria, where dozens of its contractors were killed
or injured by US air strikes in February when they undertook an ill-fated attack on a US-supported group. Their target was one of Syria's richest oil fields in Deir Ezzor province. The company has not commented on either of the cases, or any allegations levelled against it.
More recently, Wagner appears to have developed a presence in Sudan, which shares a border with CAR. In fact, Russian instructors trained some CAR soldiers in Sudan, according to a UN report. In November last year, Sudanese President Omar al-Bashir met Vladimir Putin in Sochi
and asked him for "protection from aggressive US actions" and for Russian military experts to be sent to Sudan "to reequip [Sudan's] armed forces."
In CAR, Nzilo says the Russians combine basic humanitarian works with military training and mining. He says they are visible at three major mines and appear to be most interested in extracting diamonds and gold. Another source in CAR told CNN that the Russians sometime deploy mobile clinics for the local population at the same time as contractors and military hardware.
Establishing the ownership of Russian companies involved in Syria, CAR and Sudan is difficult, but CNN has established that several lead back to Yevgeny Prigozhin
, often dubbed "Putin's chef" for his Kremlin connections.
In February, Prigozhin was indicted by a grand jury in the United States for his role in backing the "troll factory" in St. Petersburg known as the Internet Research Agency, which created fake social media accounts in the US in the run-up to the 2016 election.
Prigozhin controls a network of Russian companies, including Concord Management and Consulting. The US Treasury says Wagner is run by a man called Dmitry Utkin, who has been sanctioned. Someone of the same name used to be a director at Concord. However, both Prigozhin and Concord have in the past denied being linked to Wagner. Concord said last year: "We do not have any information about this organization."
Concord Management is challenging the designation through the US courts, while Prigozhin was quoted by state news agency RIA Novosti at the time as saying that he "couldn't care less" about the latest US sanctions
placed on him and that he would "stop going to McDonald's."
Another Russian company with interests in central Africa is M-Finans, run by 54-year old Evgueny Khodotov. Company documents describe its main activity as the "extraction of precious stones." CNN has found that M-Finans' registration data lists an email address with the same domain as a company called Concord Catering, another part of the Prighozin empire.
Khodotov used to work as a police officer in St. Petersburg's organized crime investigation unit. Many of the unit's former employees have gone on to work in security roles for Prigozhin, according to Denis Korotkov, a reporter for St. Petersburg newspaper Fontanka.ru who has been investigating Wagner activities since 2013.
And in Sudan, a Russian company by the name of M-Invest was granted concessions to mine for gold, just as President Bashir was calling for closer military cooperation. The Russian companies register shows that M-Invest, like M-Finans, is based in St. Petersburg and specializes in "extraction of ores and sands of precious metals," including gold.
The concession on behalf of M-Invest was signed by "a regional director" named as Mikhail Potepkin. A man of the same name also co-owned a company called IT-Debugger with Anna Vladislavovna Bogacheva, one of those named in US special counsel Robert Mueller's indictment
of 13 Russians who worked for the Prighozin-run Internet Research Agency. CNN was unable to contact Potepkin.
These intricate and often opaque relationships also appeared in Syria. Wagner supplied hundreds of military contractors, while another company, Evro Polis, signed a deal with the Syrian government under which it gets 25% of oil revenues
from fields that are recovered from rebel control. The US Treasury Department has designated Evro Polis
"for being owned or controlled by Yevgeny Prigozhin."
Awash with weapons
As Russia looks for opportunities to project its influence in the Middle East and Africa, countries with weak governments and rampant insecurity are obvious targets. The scale of CAR's problems -- coupled with diminishing French interest in the country -- has provided an opening for both the Kremlin and private Russian interests.
According to a UN report released on July 23, Russian contractors have distributed weapons to and trained some 900 members of CAR's security forces this year, as permitted under the arrangement reached last December. The Russian Foreign Ministry said
in March that "this assistance is provided in strict accordance with the sanctions imposed by the UN Security Council on the country."
A Russian national, Valery Zakharov, was appointed the security adviser to CAR President Faustin-Archange Touadera, and has been in discussions with some of the militias opposing the government.
But it's far from clear just what weapons the Russians have airlifted to CAR or shipped to the country through Cameroon. The UN report last month noted that "all parties concerned repeatedly committed to facilitating a detailed inspection of the stockpile stored at Camp de Roux in Bangui, but that has not yet taken place."
A diplomatic source told CNN that the shipments were "shrouded in mystery."
The UN panel also concluded
that the shipments of Russian weapons to the government had "led to waves of rearmament" among rebel groups, which have acquired assault rifles and machine guns from neighboring Sudan. A group of Russian instructors and their trainees were ambushed by a rebel group in June; one instructor was wounded.
CAR's bloody, multi-layered conflict shows little sign of ebbing. But a country traditionally close to France suddenly has a new suitor.
President Touadera met Russian Foreign Minister Sergey Lavrov at the resort of Sochi last October, just as Russian companies were being set up to do business in CAR. Touadera visited Moscow to meet Putin in May.
Moscow's ultimate intentions in the Central African Republic, one of the poorest and most volatile countries on earth, are unclear: whether to exploit the country's mineral wealth, which may also include uranium, or to plant the Russian flag in the heart of Africa, in a country that has borders with six other states.
As in Syria, there may well be a neat intersection of political ambition and profit.